Summary

In the mouse, cross-presentation is an exclusive property of the CD8α+ subset of dendritic cells (DC) but the basis for this selectivity remains unclear. Here we report that splenic CD8α+ DC are much superior to other DC subsets in internalizing dying cells in vitro. In contrast, CD8α+, CD8α– CD4+ and CD8α– CD4– DC subsets phagocytose bacteria or latex beads to a similar extent. Although CD8α+ DC are better than CD4+ DC at presenting ovalbumin (OVA)-loaded splenocytes to naïve OT-I T lymphocytes, CD4+ DC are better at presenting OVA-expressing Escherichia coli to the same T cells. In both cases, presentation is abrogated by lactacystin. These results show that both splenic CD8α+ and CD8α– DC can present exogenous antigens on major histocompatibility complex (MHC) class I via a proteasome-dependent pathway and suggest that the specialized cross-presenting function of CD8α+ DC is a result of their ability to endocytose dying cells rather than a unique pathway for handling endosomal contents.

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Publication History

Issue online: 16 October 2002

Version of record online: 16 October 2002

Received 25 June 2002; revised 29 July 2002; accepted 30 July 2002.

Supporting Information

Supplementary material to Schulz O. & Reis e Sousa C. Cross-presentation of cell-associated antigens by CD8a+ dendritic cells is attributable to their ability to internalize dead cells. Immunology 2002; 107 (2): 183?189. Please note that in order to view the movie clips below, you will need to have Apple QuickTime installed on your computer; if you don't already have this, or if the software needs updating, please visit Apple's website and download the software for free: http://www.apple.com/quicktime/download/ Video clips S1 and S2 Visualisation of dead cell uptake by CD8a+ dendritic cells (DC). CD8a+ DC were co-cultured with UV-treated, PKH26-labelled RAW cells. DC appear as phase-dense unlabelled cells of ever-changing morphology that move actively around the field whereas the dying RAW cells appear as static round cells labelled red, often seen in clusters. Images were acquired at 15 s intervals. Note the interactions of DC with clusters of dying cells and the presence of labelled material in DC as they move away.

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